Muffler construction



Dec. 14, 1965 J. B. MAlLLlE ETAL 3,223,491

MUFFLER CONSTRUCTION Filed Sept. 27. 1962 4 Sheets-Sheet 1 FIG.|

FlG. 4 W 23 67 Dec. 14, 1 J. B. MAlLLlE ETAL MUFFLER CONSTRUCTION 4Sheets-Sheet 2 Filed Sept. 27, 1962 1965 J. B. MAILLIE ETAL 3,223,491

MUFFLER CONSTRUCTION 4 Sheets-Sheet 3 Filed Sept. 27, 1962 F|G.7 4a 4 23V /1 \m [7i E I United States Patent Ohio, a corporation of Ohio FiledSept. 27, 1962, Ser. No. 226,709 2 Claims. (Cl. 23--288) The inventionrelates generally to catalytic apparatus for eliminating obnoxiousvehicle exhaust emissions by oxidation, and more particularly to acatalytic apparatus adapted for connection to the exhaust pipe of aninternal combustion engine to replace the conventional mufiier, thuseliminating noise as well as fumes.

Catalytic muffiers have a number of requirements, which makes theconstruction of a practical, etficient and economical muffler for thispurpose a difllcult and complicated problem. The mufller shell must beof practical and reasonable dimensions, must not create excessive backpressure on the engine, must provide properly distributed contactbetween the exhaust gases and the catalytic material, must be rugged towithstand mechanical shocks in use and minimize distortion, and mustprovide for differential expansion between the outer parts and the innerparts where high temperatures are generated due to oxidation.

In addition, problems arise because the catalytic material is preferablyin the form of granules or pellets, and must be supported in arelatively thin layer or bed, preferably in slightly tilted,substantially horizontal position, in such manner as to avoid excessivepressure drop and gas leakage in normal operation, while providing forpositive by-passing of the bed by the gases in case of abnormalsituations, such as fouled spark plugs, which would create excessive bedtemperatures, damaging the catalyst as well as the muflier.

The temperatures required for catalytic oxidation of vehicle emissionsare upwards of 1000 F., necessitating the use of stainless steel parts,at least in and adjacent to the catalytic bed, but even suchhigh-temperature alloys require substantial intermediate support toprevent sagging and distortion, and there is the ever-present problem ofcompensating for differential expansion without excessive use of costlymetal.

Certain prior catalytic mufflers have been proposed which meet asubstantial number of the foregoing requirements, but said priorconstructions have been diflicult and expensive to fabricate, involvinglaborious hand operations, uneconomic use of stainless steel, and anexcessive number of parts. They have also inhibited the free spread ofcatalytic action and created turbulence in the flow of exhaust gasestherethrough.

A general object of the present invention is to provide a novel andimproved catalytic muffler construction which will meet the foregoingrequirements, which will be more efficient in operation, and which canbe simply and economically fabricated with a minimum of material andlabor.

Specifically, an object of the present invention is to provide acatalytic mufiler construction which utilizes a minimum number of partsand lends itself to fabrication by automatic welding operations.

Another object is to provide an improved construction for solidlysupporting the catalytic bed while minimizing distortion andcompensating for differential expansion of the parts thereof relative tothe muflier shell.

A further object is to provide an improved light-weight central beamconstruction for preventing sagging while permitting free spread ofcatalytic action throughout the bed.

3,223,491 Patented Dec. 14, 1965 Another object is to provide animproved deflector valve arrangement for selectively by-passing flow ofexhaust gases around the bed.

A further object is to provide an improved mufller construction forfacilitating easy replacement of the catalytic material in the bed.

A still further object is to provide an improved mufller constructionwhich promotes smooth, non-turbulent flow of exhaust gases to and fromthe catalytic bed.

These and other objects are accomplished by the parts, constructions andcombinations comprising the present invention, a preferred embodiment ofwhich is shown in the drawings and described herein as an example of thebest known mode of carrying out the invention. Various modifications andchanges in details of construction are embraced within the scope of theappended claims.

The improved catalytic muffler comprising the present invention consistsof a flattened tubular one-piece body shell surrounding a rectangularconstruction of channels and perforate grids containing a bed ofcatalytic material, the bed structure being spaced from the top andbottom of the body shell to form gas inlet and discharge ducts. Centrallongitudinal embossments formed inwardly top and bottom in the bodyshell are welded to an open, nonwarpable, bed-supporting beam in the bedstructure in such manner as to permit differential expansion between theshell, the beam and the bed structure. The perforate grids of the bedstructure are slidably supported both peripherally and along thelongitudinal beam. Inlet and outlet end shells, attached to the bodyshell by welded mating peripheral flanges, provide smooth, non-turbulentgas flow to and from the bed. The mated flanges provide positivelocation for a wrap-around thermal insulation blanket and means forattaching its protective cover. A simplified deflector valve is mountedin the inlet end shell for selectively by-passing flow of exhaust gasesaround the bed.

Referring to the drawings:

FIG. 1 is a plan view of a catalytic muflier embodying the presentinvention.

FIG. 2 is a side elevation thereof.

FIG. 3 is a front end elevation thereof.

F IG. 4 is a rear end elevation thereof.

FIG. 5 is an enlarged longitudinal sectional view, parts being brokenaway.

FIG. 6 is a cross sectional view on line 66 of FIG. 5.

FIG. 7 is a further enlarged view of a portion of FIG. 5.

FIG. 8 is an enlarged view of a portion of FIG. 2 partly broken away andin section.

FIG. 9 is a fragmentary enlarged plan sectional view of the inletportion of the mufiier, with parts broken away.

FIG. 10 is an elevation on line 1010 of FIG. 5, of the by-pass deflectorvalve removed from the muffler.

FIG. 11 is a transverse sectional view on line 11-11 of FIG. 9, withparts removed.

FIG. 12 is a fragmentary sectional view of the filler tube in the rearend.

FIG. 13 is a detached fragmentary perspective View of the expansiblebearing strip between the grids and the central beam.

Referring first to FIGS. l4, the improved catalytic mufiler comprises aflattened elongated body 20, substan-' tially rectangular in allelevations and having tapered end shells 21 and 23 attached to its inletand outlet ends, respectively. Inlet end shell 21 preferably has a usualattaching flange 22 for bolting to a similar flange on the exhaust pipe(not shown) of an internal combustion engine. Outlet end shell 23 isattached to the other end of the body 20 and preferably terminates in acylindrical exhaust pipe 25.

3 As shown in FIGS. 5 and 6, the body 20 comprises an inner bedstructure including spaced-apart upper and lower grids 26 and 27 with acentral longitudinal beam ,or web 28 extending vertically between thegrids, a body shell 29 surrounding said bed in vertically spacedrelation to said grids, and ametal cover 30 enclosing a blanket 31 ofthermal insulation material wrapped around the body shell 29.

The upper and lower grids are foraminous plates; that is, they have amultiplicity of openings or perforations formed in the plates in anysuitable manner. The openings are large enough to permit through flow ofgases but small enough to prevent escape of the catalyst granules.

The body shell 29 is preferably a single piece of sheet metal, which isformed into a flat tubular shape and seamwelded at any convenientlocation (not shown). The body shell is vertically spaced above grid 26and below grid 27 to form gas inlet and outlet ducts 38 and 39,respectively. Preferably, the grids 26 and 27 are inclined slightly withrespect to the top and bottom portions of the shell, so that the duct 38is relatively deep at its inlet end 38A and relatively shallow at itsopposite end 38B, while duct 39 is relatively shallow at the inlet end39A and relatively deep at the opposite or outlet end 39B. Exhaust gasesnormally enter inlet end 38A, and due to the inclination of the bed aremore effectively and uniformly directed into and through the bed.

The upper portion of body shell 29 has a central longitudinal embossmentor channel 40 formed inwardly thereof, and the lower portion of bodyshell 29 has a central longitudinal embossment or channel 41 formedinwardly thereof. The inward faces of embossments 40 and 41 intermediatetheir ends rest against the upper and lower grids 26 and 27,respectively, and the end portions 40A, 40B and 41A, 41B of theembossments taper outwardly and terminate at the peripheral flanges 42and 43 which extend continuously around the inlet and outlet ends,respectively, of the body shell 29. The intermediate portions ofembossments 40 and 41 vary in depth to accommodate the inclination ofthe grids 26 and 27 with respect to the body shell 29.

The novel one-piece body shell with outwardly flanged ends eliminatesperipheral trim waste and gas port punchout waste inherent in priorconstructions using deep drawn half shells, and eliminates expensivewelding entirely around the outer periphery of the mufller by requiringwelding only one longitudinal seam. Moreover, the improved one-pieceshell provides for positive attachment of the insulation cover locatingthe insulation blanket, and for cam-programmed automatic welding of theshell to the end shells.

The central beam or web 28 is preferably substantially co-extensive withthe intermediate portions of embossments 40 and 41 and terminatesadjacent to the start of the tapered end portions, so that longitudinalexpansion and contraction of the beam is minimized while providingadequate support for the grids 26 and 27. Large openings 44 are providedthrough the beam at longitudinal intervals between welds attaching thebeam to the body shell 29. These openings serve to provide communicationbetween both sides of the bed to permit spread of catalytic actionthroughout the bed, as well as to facilitate rapid filling and removingof catalytic material. Further, the openings 44 Weaken the web betweenweldments and provide for incremental take-up of the Webs longitudinalexpansion by slight lateral bending of the weakened portions. The beam28 being fore-shortened at both ends substantially reduces the amount ofstainless steel required for central support in previous designs.

Longitudinally expansible bearing strips 45 are preferably interposedbetween the edges of perforated center beam 28 and the inner surfaces ofgrids 26 and 27, for the purpose of providing continuous support tosame. As shown in FIGS. 5, 6, 7 and 13, these strips have longitudinalslots 46 at longitudinal intervals through which projections 47 on thebeam 28 extend. The projections 47 continue into further steppedprojections 48 which extend through accommodating longitudinal slots 49in the intermediate bottom portions of embossments and 41 and areattached thereto. The projections 47 also project through the grids 26and 27 (FIG. 7), via longitudinal slots which are long enough to permitdifferential expansion movement between the beam and the grids. Theshoulders formed between projections 47 and stepped projections 48locate and support the body shell embossments 40 and 41 during assembly.

Between the slots 46 the bearing strips are provided with staggeredtransverse edge-opening slots 51A and 51B, which take up the stripslongitudinal expansion movements incrementally between beam projections47. The bearing strips 45 widen the continuous bearing area between thebeam edges and the grids to prevent sagging, and also prevent catalystgranules from working their way into the ends of grid slots where theywould be subject to crushing due to differential expansion. Thus, thegrids are free to move longitudinally and the differential longitudinalexpansion between the cool body shell and the hot beam-and-bearing-stripstructure is divided into a plurality of small harmless increments.

The insulation cover 30 is preferably an aluminum sheet wrapped aroundthe body shell 29 in spaced relation to enclose the thermal insulatingblanket 31 engirdling the body shell 29. The cover 30 is preferablylock-seamed at any convenient location (not shown), and its ends areformed into inward peripheral flanges 52 and 53 for locking engagementwith the shell flanges. The cover 30 thus secures the insulation blanket31 on the mufller and seals its ends against road splash.

The side edges of grids 26 and 27 are slidably received in longitudinalslots formed between the legs 55 and 56 of nested channels 57 and 58extending longitudinally along the side wall portions 59 of body shell29. The inner channels 57 are welded at longitudinal intervals to theouter channels 58 and the webs of the inner channels are provided withopenings 60 between weldments, so that the nested channel assemblies canbe attached to the side wall portions 59 by spot welding the outerchannels to the shell through the openings 60. This avoids thedifliculties of welding through three thicknesses of metal.

The end edges of grids 26 and 27 are similarly received in transverselyextending slots formed between the legs 55" and 56' of nested channels57' and 58' extending transversely of the ends of the grids and closedat their ends against the ends of side channels 57 and 58. The Webs ofinner channels 57' are provided with welding openings 60' through whichthe outer channels 58' can be spot welded to the end shells 21 and 23,respectively. As seen in FIG. 5, the channel 58' at the outlet end iswelded to the upper flat portion of outlet end shell 23; and the channel58 at the inlet end is welded in its laterally central portion to thevertical flange 62 of inclined partition 63 in the inlet end shell 21,and welded near its ends to inward projections of flange 64 of inlet endshell 21, as seen in FIG. 11.

The inlet end shell 21 tapers outwardly from the circular opening 22' inits attaching flange 22 to flat substantially rectangular shapes top andbottom, as shown in FIG. 11, and it terminates in a peripheral flange 64mating with peripheral flange 42 on body shell 29. Preferably, flanges42 and 64 are welded together by an automatic welding operation.

As seen in FIGS. 9 and 11, the flat outward tapers of inlet shell 21form lateral transition chambers which communicate with upper and lowergas ducts 68 and 69, and they are separated by a central chamber formedsubstantially by vertical side walls 66 and 67. The transition chambersare smoothly tapered to avoid the turbulence created in many priordesigns, with resultant increase in back pressure. Moreover, lessmaterial and labor and a minimum of welding (all automatic) is required.The

inclined partition 63 extends laterally between the walls 66 and 67, andits laterally curved lower edge 70 conforms to and is through-weldedagainst a curved inset 71 formed jaw-fashion in the lower portion ofinlet shell 21. The upper portion of partition 63 is bent rearwardlydownward to form the transverse attaching flange 62, thus completing thesealed separation of flow chambers communicating with upper and lowergas ducts 68 and 69.

The partition 63 has a preferably circular valve port 72 formedcentrally therein, and a substantially semicircular deflector valve 73is provided with a spherically shaped embossment 73 which normally seatsin valve port 72, as shown in FIG. 5, closing off the entrance of gasflow to the lower transition chamber and the lower gas duct 39A. Thedeflector valve 73 is pivotally mounted from its underside on a shaft 74by means of an arm 75 attached to a center post 76 in the sphericallyembossed portion of the valve, for swinging to the dotted line position.The shaft 74 is journaled at its inner end in a bearing 77 formed in abracket 78 attached to flange 62, and the shaft extends through agas-tight bearing 79 in side wall 66.

The outer end of shaft 74 has a lever arm 80 thereon which is pivoted atits outer end by a pin and slot connection 81 (FIG. 8) to the operatingarm 82 connected to the diaphragm of a conventional vacuum booster 83mounted on a bracket 84 attached to the flange 64 of inlet end shell 21.The arm 82 normally holds the lever 80 in the full line position ofFIGS. 5 and 8 to hold deflector valve 73 closed, and it swings to thedotted line position to direct the gas flow on a bypass course aroundthe catalyst when necessary to prevent over-heating.

The improved one-piece deflector valve utilizes a minimum of material,and the location of its pivotal mounting on the underside eliminates anyobstacles to normal gas flow. The interior bearing 77 reduces the numberof exterior wall gas-tight bearings to one instead of two, as in manyprior constructions.

The by-pass system is preferably controlled by the temperature of thecatalytic material in the bed between the grids 26 and 27. As shown inFIG. 1, a thermocouple probe 86 may be inserted through the upper flatportion of outlet end shell 23, extending into the central portion ofthe catalytic bed. The thermocouple 86 is calibrated to actuate athermal switch 87 at a predetermined maximum temperature above which thebed structure or the catalytic material or both would be damaged. Theswitch 87 is electrically connected to activate the vacuum boosterduring normal operation of the muflier. When high temperatures threaten,the switch shuts off the vacuum and permits the usual diaphragm-opposingspring in the booster to open the by-pass valve.

The flat portion 23 of the outlet end shell is readily adapted toaccommodate a filling tube 92 extending through rear channels 57 and 58'and opening direcfly into the space between grids 26 and 27 for fillingor replacing catalytic material forming the bed. A suitable cap 93normally closes the tube. Thus, the filler opening, as Well as thethermocouple opening, is directly accessible to the catalytic bed ratherthan through the thermal insulation blanket and cover which are requiredwhen inserted from the side of the mufller.

The location of the thermal switch and filler tube at the rear end ofthe muflier above the transition chamber 24 of the outlet end shellprotects them from road damage from flying stones and the like, and italso simplifies packaging or palletizing the mufflers for shipment.

The transition chambers 21 and 24 of the inlet and outlet end shellsprovide smooth, gradual transition of gas flow from the exhaust pipeopening 22' into the upper gas duct 38 (or via 21' into the lower gasduct 39 during by-pass), and from the lower gas duct 39 to the tail pipe25, without requiring punched out gas flow openings in the body shell,the ragged edges of which tend to create turbulence in the gas flow.

In the operation of the improved catalytic muflier, the exhaust gasesentering the inlet end shell 21 flow through port 22' and are deflectedupwardly by the deflector valve 73 in its normal closed position intothe entrance end 38A of upper gas duct 38. The hot gases flow uniformlyover the entire upper surface of inclined upper grid 26 and pass throughthe openings 35 therein into and through the bed of catalytic materialcontained between grids 26 and 27. The catalytic material causesoxidation of noxious exhaust emissions, resulting in temperatures of theorder of 1000-1400 F. The gaseous products ofcombustion flow throughlower grid 27 into the lower gas duct 39, and thence out through thetransition chamber 24 of outlet end shell 23 and exhaust pipe 25.

The construction of the improved catalytic mufller is such as to reduceor muflle the sound of the exhaust from the engine, so that it performsthe dual function of reducing noise and eliminating fumes.

If the temperature of the bed is unduly elevated by excess hydrocarbonsin the exhaust gases, e.g., caused by a fouled spark plug or carburetormalfunction, the thermocouple will actuate the switch 87 to cut off thevacuum and permit the diaphragm-opposing spring (not shown) to movedeflector valve 73 to its upper position, closing the upper transitionchamber to gas duct 38 and opening the lower transition chamber to gasduct 39 to the direct flow of exhaust gases, thus by-passing thecatalytic bed. As soon as the bed temperature returns to normal, thethermocouple actuates switch 87 to reinstate the vacuum and the vacuumbooster diaphragm movement returns the deflector valve to normalposition, deflecting flow into upper gas duct 38.

The improved catalytic mufller is simple and inexpensive to fabricateand service, embodies a minimum number of parts and a minimum quantityof material, and it minimizes distortion and sagging due to highoperating temperatures. It also provides smooth flow transitions andminimizes back pressures due to turbulence. Moreover, it effectivelyremoves noxious exhaust emissions and eliminates engine exhaust noise,while providing compact and rugged construction highly resistant toshocks and impact.

What is claimed is:

1. Catalytic muffler construction for exhaust gases comprising, upperand lower foraminous grids having spaced longitudinal slots and formingan elongated flattened bed structure for enclosing catalyst material, aone-piece body shell surrounding said upper and lower grids and havingperipheral flanges at either end, longitudinal inward embossments formedin said body shell exteriorly of said grids, a longitudinal perforatedcenter beam between said grids extending a portion of the lengththereof, spaced projections on the edges of said longitudinal perforatebeam extending through said spaced slots in said grids and attached tosaid longitudinal inward embossments of said body shell, bearing stripsinterposed between said longitudinal center beam and the inner surfacesof said grids, whereby said grids are movably supported and thecatalytic material is restricted from escaping into the slots of saidgrids, end shells having peripheral flanges mating with and attached tothe peripheral flanges on said body shell and providing tapered flowtransitions, and means on the interior of said body shell and end shellssealing the periphery of said grids against the escape of catalystmaterial.

2. Catalytic muflier construction in accordance with claim 1 whereinsaid means on the interior of said body shell and end shells sealing theperiphery of said grids against the escape of catalyst materialcomprises nested channels which matingly engage the peripheral edges ofsaid upper and lower grids.

(References on following page) 7 References Cited by the Examiner3,024,593 UNITED STATES PATENTS ggggggi 8/1926 Cornelier 23288 0 6 3911/1949 Sills. 5 3 090: 7; 1/1957 Houdry 232 8 3 094 394 10/ 1957Bratton. 3 097 074 5/1958 Houdry 23288 9/1958 Karol et a1. 23288 8/1959Houdry et a1 23288 10 448,850 10/1959 Houdry 23288 7/1961 Claussen 232883/ 1962 Houdry.

8/ 1962 Eastwood.

3/1963 Raymond 23288 4/1963 Bloch 23288 XR 5/1963 Scheitlin et a1 232886/1963 Innes et a1. 231288 7/1963 Johnson 23288 FOREIGN PATENTS 6/ 1936Great Britain.

MORRIS O. WOLK, Primary Examiner.

1. CATALYTIC MUFFLER CONSTRUCTION FOR EXHAUST GASES COMPRISING, UPPERAND LOWER FORAMINOUS GRIDS HAVING SPACED LONGITUDINAL SLOTS AND FORMINGAN ELONGATED FLATTENED BED STRUCTURE FOR ENCLOSING CATALYST MATERIAL, AONE-PIECE BODY SHELL SURROUNDING SAID UPPER AND LOWER GRIDS AND HAVINGPERIPHERAL FLANGES AT EITHER END, LONGITUDINAL INWARD EMBOSSMENTS FORMEDIN SAID BODY SHELL EXTERIORLY OF SAID GRIDS, A LONGITUDINAL PERFORATEDCENTER BEAM BETWEEN SAID GRIDS, A LONGITUDINAL PERFORATED CENTER BEAMBETWEEN SAID GRIDS EXTENDING A PORTION OF THE LENGTH THEREOF, SPACEDPROJECTIONS ON THE EDGES OF SAID LONGITUDINAL PERFORATE BEAM EXTENDINGTHROUGH SAID SPACED SLOTS IN SAID GRIDS AND ATTACHED TO SAIDLONGITUDINAL INWARD EMBOSSMENTS OF SAID BODY SHELL, BEARING STRIPSINBTERPOSED BETWEEN SAID LONGITUDINAL CENTER BEAM AND THE INNER SURFACESOF SAID GRIDS, WHEREBY SAID GRIDS ARE MOVABLY SUPPORTED AND THECATALYTIC MATERIAL IS RESTRICTED FROM ESCAPING INTO THE SLOTS OF SAIDGRIDS, END SHELLS HAVING PERIPHERAL FLANGES MATING WITH AND ATTACHED TOTHE PERIPHERAL FLANGES MATING WITH AND ATTACHED TO THE PERIPHERALFLANGES ON SAID BODY SHELL AND PROVIDING TAPERED FLOW TRANSITIONS, ANDMEANS ON THE INTERIOR OF SAID BODY SHELL AND END SHELLS SEALING THEPERIPHERY OF SAID GRIDS AGAINST THE ESCAPE OF CATALYST MATERIAL.